There is something in the GAC that LV doesn't like. I don't know how well the b2 uninstall works but that is the only thing I know that can cause the window to lock.
You can try this...Be careful about deleting anything but uninstalling should leave the following directories empty.
1. Uninstall all .NET frameworks from the Add/Remove (1.0, 1.1 and 2.0). Reboot.
2. Go to \Windows\Assembly\GAC via a command window (cmd.exe) (not windows explorer) and see if there are any subdirectories. If you have installed .NET applications, they may have installed components there. If so, you may need to uninstall and reinstall those after this sequence is complete. If that is going to be too difficult, let me know and I can walk you through a more involved process. Hopefully that won't be necessary.
- You should be able to delete the Assembly directory at this point. You should also be able to delete the c:\Windows\Microsoft.NET directory also. Again, check to see if there is anything left in there before deleting.
3. Install the 1.1 framework.
4. Try LV again.